I was under the impression that they stopped selling the Tosfot style due to lack of demand and those who want to wear it just buy two sets of Raavad.
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Double AA♦Jan 9 '12 at 6:09

I would just like to point out, that once you have techelet, and you look into the way you tie the knots. The number of blue strings only works for the type of knot you tie. Meaning, if you tie like rambam, using two blue strings is impossible. If you tie like Rav Amran Hagaon, then using 1 full blue string also makes no sense.
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aviJan 9 '12 at 7:07